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Nitrogen dioxide, NO2, and dinitrogen tetroxide, N2O4, form an equilibrium mixture represented by the following equation - VCE - SSCE Chemistry - Question 19 - 2020 - Paper 1
Question 19
Nitrogen dioxide, NO2, and dinitrogen tetroxide, N2O4, form an equilibrium mixture represented by the following equation. 2NO2(g) ⇌ N2O4(g) ΔH = -57.2 kJ mol⁻¹ A ... show full transcript
Worked Solution & Example Answer:Nitrogen dioxide, NO2, and dinitrogen tetroxide, N2O4, form an equilibrium mixture represented by the following equation - VCE - SSCE Chemistry - Question 19 - 2020 - Paper 1
Step 1
Which one of the following describes the change that was made to the initial equilibrium system and the colour change that occurred between t1 and t2?
Answer
To analyze the effect of temperature on the equilibrium position and color of the system, we must consider Le Chatelier's principle, which states that if a system at equilibrium is subjected to a change in temperature, pressure, or concentration, the system will adjust to counteract that change.
In the given reaction, since the formation of N2O4 from NO2 is exothermic (indicated by the negative ΔH), increasing the temperature will favor the endothermic direction, which is the reverse reaction (decomposition of N2O4 into NO2). Consequently, the concentration of NO2 will increase and the equilibrium will shift towards the brown color of NO2.
Thus, if the temperature was increased, we would expect the colour to darken, as more NO2 (the brown gas) is produced.
Therefore, the correct answer is B. The temperature was increased and the colour darkened.